<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			div{
				width: 200px;
				height: 200px;
				background-color: dodgerblue;
				border: 10px solid gray;
				box-sizing: border-box;
				padding: 20px;
			}
		</style>
	</head>
	<body>
		<div>宽和高应用到元素边框</div>
	</body>
</html>
